Co2 refrigeration system with magnetic refrigeration system cooling

ABSTRACT

A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a divisional application of and claims priorityunder 35 U.S.C. § 120 to U.S. application Ser. No. 16/421,819, filed onMay 24, 2019, which claims the benefit of and priority to U.S.Provisional Patent Application No. 62/680,879 filed Jun. 5, 2018, theentire contents of each of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates generally to a refrigeration systemprimarily using carbon dioxide (i.e., CO₂) as a refrigerant. The presentdisclosure relates more particularly to a CO₂ refrigeration system witha magnetic refrigeration system that provides after-cooling,desuperheating, or other efficiency enhancements for the CO₂refrigeration system.

Refrigeration systems are often used to provide cooling to temperaturecontrolled display devices (e.g. cases, merchandisers, etc.) insupermarkets and other similar facilities. Vapor compressionrefrigeration systems are a type of refrigeration system which providessuch cooling by circulating a fluid refrigerant (e.g., a liquid and/orvapor) through a thermodynamic vapor compression cycle. In a vaporcompression cycle, the refrigerant is typically (1) compressed to a hightemperature high pressure state (e.g., by a compressor of therefrigeration system), (2) cooled/condensed to a lower temperature state(e.g., in a gas cooler or condenser which absorbs heat from therefrigerant), (3) expanded to a lower pressure (e.g., through anexpansion valve), and (4) evaporated to provide cooling by absorbingheat into the refrigerant. CO₂ refrigeration systems are a type of vaporcompression refrigeration system that use CO₂ as a refrigerant.

SUMMARY

One implementation of the present disclosure is a refrigeration systemincluding a refrigeration circuit and a coolant circuit separate fromthe refrigeration circuit. The refrigerant circuit includes a gascooler/condenser configured to remove heat from a refrigerantcirculating within the refrigeration circuit and having an outletthrough which the refrigerant exits the gas cooler/condenser, a receiverhaving an inlet fluidly coupled to the outlet of the gascooler/condenser and configured to collect the refrigerant from the gascooler/condenser and having an outlet through which the refrigerantexits the receiver, and an evaporator having an inlet fluidly coupled tothe outlet of the receiver and configured to receive the refrigerantfrom the receiver and transfer heat into the refrigerant circulatingwithin the refrigeration circuit. The coolant circuit includes a heatexchanger configured to transfer heat from the refrigerant circulatingwithin the refrigeration circuit into a coolant circulating within thecoolant circuit. The heat exchanger includes a coolant inlet throughwhich the coolant enters the heat exchanger and a coolant outlet throughwhich the coolant exits the heat exchanger. The coolant circuit includesa heat sink configured to remove heat from the coolant circulatingwithin the coolant circuit. The heat sink includes an inlet fluidlycoupled to the coolant outlet of the heat exchanger and through whichthe coolant enters the heat sink and an outlet fluidly coupled to thecoolant inlet of the heat exchanger and through which the coolant exitsthe heat sink. The coolant circuit includes a magnetocaloricconditioning unit configured to transfer heat from the coolant within afirst fluid conduit of the coolant circuit into the coolant within asecond fluid conduit of the coolant circuit. The first fluid conduitfluidly couples the coolant outlet of the heat exchanger to the inlet ofthe heat sink, whereas the second fluid conduit fluidly couples theoutlet of the heat sink to the coolant inlet of the heat exchanger.

In some embodiments, the magnetocaloric conditioning unit is configuredto perform a magnetocaloric refrigeration cycle using changing magneticfields to transfer the heat from the coolant within the first fluidconduit into the coolant within the second fluid conduit.

In some embodiments, the heat exchanger is positioned along a fluidconduit of the refrigeration circuit connecting the outlet of the gascooler/condenser to the inlet of the receiver.

In some embodiments, the refrigeration circuit includes a high pressurevalve positioned along the fluid conduit connecting the outlet of thegas cooler/condenser to the inlet of the receiver. The heat exchangermay be positioned between the gas cooler/condenser and the high pressurevalve to provide additional cooling for the refrigerant exiting the gascooler/condenser before the refrigerant reaches the high pressure valve.

In some embodiments, the refrigeration circuit further includes a highpressure valve positioned along the fluid conduit connecting the outletof the gas cooler/condenser to the inlet of the receiver. The heatexchanger may be positioned between the high pressure valve and thereceiver to provide cooling for the refrigerant traveling from the highpressure valve to the receiver.

In some embodiments, the heat exchanger is positioned along a fluidconduit of the refrigeration circuit connecting the outlet of thereceiver to the inlet of the evaporator to subcool the refrigerantexiting the receiver before the refrigerant reaches the evaporator.

In some embodiments, the coolant circuit includes a bypass conduitfluidly coupling the second fluid conduit of the coolant circuit to thefirst fluid conduit of the coolant circuit in parallel with the heatexchanger, thereby providing an alternative flow path for the coolant totravel from the second fluid conduit to the first fluid conduit withoutpassing through the heat exchanger. The coolant circuit may include acontrol valve positioned along the bypass conduit and operable tocontrol a flow of the coolant through at least one of the bypass conduitand the heat exchanger.

In some embodiments, the refrigeration system includes a temperaturesensor positioned along the first fluid conduit between themagnetocaloric conditioning unit and a location at which the bypassconduit and the first fluid conduit intersect. The refrigeration circuitmay include a controller configured to operate the control valve tomaintain a temperature of the coolant measured by the temperature sensorat or below a temperature setpoint by varying an amount of the coolantpermitted to bypass the heat exchanger via the bypass conduit.

In some embodiments, the refrigeration circuit includes one or morecompressors configured to compress the refrigerant and discharge thecompressed refrigerant into a compressor discharge line. The heatexchanger may be positioned along the compressor discharge line andconfigured to remove heat from the compressed refrigerant in thecompressor discharge line.

In some embodiments, the refrigeration system includes a control valveoperable to control a flow of the coolant through the heat exchanger anda controller configured to operate the control valve to maintain asuperheat of the refrigerant exiting the heat exchanger at apredetermined superheat setpoint by varying an amount of heat removedfrom the compressed refrigerant in the heat exchanger.

In some embodiments, the refrigeration system includes a control valveoperable to control a flow of the coolant through the heat exchanger anda controller configured to operate the control valve to cause thecompressed refrigerant in the heat exchanger to fully condense to aliquid refrigerant by controlling an amount of heat removed from thecompressed refrigerant in the heat exchanger.

In some embodiments, the heat exchanger includes a refrigerant outletfluidly coupled to the receiver and configured to deliver the liquidrefrigerant from the heat exchanger to the receiver.

In some embodiments, the coolant circuit includes a plurality of heatexchangers configured to transfer heat from the refrigerant circulatingwithin the refrigeration circuit into the coolant circulating within thecoolant circuit. The plurality of heat exchangers may include a firstheat exchanger positioned along a fluid conduit of the refrigerationcircuit connecting the outlet of the gas cooler/condenser to the inletof the receiver to provide additional cooling for the refrigeranttraveling from the gas cooler/condenser to the receiver and a secondheat exchanger positioned along a compressor discharge line of therefrigeration circuit and configured to remove heat from the refrigerantin the compressor discharge line.

In some embodiments, the refrigeration circuit includes one or morecompressors configured to receive the refrigerant from a compressorsuction line, compress the refrigerant, and discharge the compressedrefrigerant into a compressor discharge line. The heat exchanger may bepositioned along the compressor suction line and configured to removeheat from the compressed refrigerant in the compressor suction line.

In some embodiments, the heat removed from the refrigerant in the heatexchanger causes the refrigerant to at least partially condense into aliquid or a mixture of liquid and gas. The refrigeration circuit mayinclude a liquid/vapor separator fluidly coupled to a refrigerant outletof the heat exchanger and configured to separate a liquid portion of therefrigerant exiting the heat exchanger from a gas portion of therefrigerant exiting the heat exchanger.

In some embodiments, the liquid/vapor separator includes a liquidrefrigerant outlet fluidly coupled to the inlet of the receiver andconfigured to deliver the liquid portion of the refrigerant to thereceiver and a gas refrigerant outlet fluidly coupled to the compressorsuction line and configured to deliver the gas portion of therefrigerant to the compressor suction line.

Another implementation of the present disclosure is a magneticrefrigeration system including a heat exchanger, a heat sink, and amagnetocaloric conditioning unit. The heat exchanger is configured totransfer heat from a refrigerant circulating within a refrigerationcircuit into a coolant circulating within a coolant circuit and includesa coolant inlet through which the coolant enters the heat exchanger anda coolant outlet through which the coolant exits the heat exchanger. Theheat sink is configured to remove heat from the coolant circulatingwithin the coolant circuit. The heat sink includes an inlet fluidlycoupled to the coolant outlet of the heat exchanger and through whichthe coolant enters the heat sink and an outlet fluidly coupled to thecoolant inlet of the heat exchanger and through which the coolant exitsthe heat sink. The magnetocaloric conditioning unit is configured totransfer heat from the coolant within a first fluid conduit of thecoolant circuit into the coolant within a second fluid conduit of thecoolant circuit. The first fluid conduit fluidly couples the fluidoutlet of the heat exchanger to the inlet of the heat sink, whereas thesecond fluid conduit fluidly coupling the outlet of the heat sink to thecoolant inlet of the heat exchanger.

In some embodiments, the magnetocaloric conditioning unit is configuredto perform a magnetocaloric refrigeration cycle using changing magneticfields to transfer the heat from the coolant within the first fluidconduit into the coolant within the second fluid conduit.

In some embodiments, the magnetic refrigeration system includes acontrol valve operable to control a flow of the coolant through the heatexchanger and a controller configured to operate the control valve tomaintain a superheat of the refrigerant exiting the heat exchanger at apredetermined superheat setpoint by varying an amount of heat removedfrom the refrigerant in the heat exchanger.

In some embodiments, the magnetic refrigeration system includes acontrol valve operable to control a flow of the coolant through the heatexchanger and a controller configured to operate the control valve tocause the refrigerant in the heat exchanger to fully condense to aliquid refrigerant by controlling an amount of heat removed from therefrigerant in the heat exchanger.

The foregoing is a summary and thus by necessity containssimplifications, generalizations, and omissions of detail. Consequently,those skilled in the art will appreciate that the summary isillustrative only and is not intended to be in any way limiting. Otheraspects, inventive features, and advantages of the devices and/orprocesses described herein, as defined solely by the claims, will becomeapparent in the detailed description set forth herein and taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a CO₂ refrigeration system with amagnetic refrigeration system after-cooler, according to an exemplaryembodiment.

FIG. 2 is a schematic diagram of the CO₂ refrigeration system of FIG. 1with a bypass line and control valve to bypass the after-cooler of themagnetic refrigeration system, according to an exemplary embodiment.

FIG. 3 is a schematic diagram of another CO₂ refrigeration system with amagnetic refrigeration system after-cooler and desuperheater, accordingto an exemplary embodiment.

FIG. 4 is a schematic diagram of another CO₂ refrigeration system with amagnetic refrigeration system as a medium temperature suction condenserapplied with a liquid ejector, according to an exemplary embodiment.

FIG. 5 is a schematic diagram of another CO₂ refrigeration system with amagnetic refrigeration system as a low temperature discharge gascondenser and flash gas condenser applied with parallel compression,according to an exemplary embodiment.

FIG. 6 is a schematic diagram of another CO₂ refrigeration system with amagnetic refrigeration system to subcool supply liquid exiting areceiver, according to an exemplary embodiment.

FIG. 7 is a schematic diagram of another CO₂ refrigeration system with amagnetic refrigeration system to convert flash gas to liquid beforeentering a receiver, according to an exemplary embodiment.

DETAILED DESCRIPTION

CO₂ Refrigeration System with Magnetic Refrigeration System After-Cooler

Referring to FIGS. 1-2, a CO₂ refrigeration system 100 is shownaccording to an exemplary embodiment. CO₂ refrigeration system 100 maybe a vapor compression refrigeration system which uses primarily carbondioxide (CO₂) as a refrigerant. CO₂ refrigeration system 100 and isshown to include a system of pipes, conduits, or other fluid channels(e.g., fluid conduits 1, 3, 5, 7, 9, 13, 23, and 25) for transportingthe CO₂ refrigerant between various thermodynamic components of CO₂refrigeration system 100. The thermodynamic components of CO₂refrigeration system 100 are shown to include a gas cooler/condenser 2,a high pressure valve 4, a receiver 6, a gas bypass valve 8, amedium-temperature (“MT”) subsystem 10, and a low-temperature (“LT”)subsystem 20.

Gas cooler/condenser 2 may be a heat exchanger or other similar devicefor removing heat from the CO₂ refrigerant. Gas cooler/condenser 2 isshown receiving CO₂ gas from fluid conduit 1. In some embodiments, theCO₂ gas in fluid conduit 1 may have a pressure within a range fromapproximately 45 bar to approximately 100 bar (i.e., about 650 psig toabout 1450 psig), depending on ambient temperature and other operatingconditions. In some embodiments, gas cooler/condenser 2 may partially orfully condense CO₂ gas into liquid CO₂ (e.g., if system operation is ina subcritical region). The condensation process may result in fullysaturated CO₂ liquid or a two-phase liquid-vapor mixture (e.g., having athermodynamic vapor quality between 0 and 1). In other embodiments, gascooler/condenser 2 may cool the CO₂ gas (e.g., by removing superheat)without condensing the CO₂ gas into CO₂ liquid (e.g., if systemoperation is in a supercritical region). In some embodiments, thecooling/condensation process is an isobaric process. Gascooler/condenser 2 is shown outputting the cooled and/or condensed CO₂refrigerant into fluid conduit 3.

High pressure valve 4 receives the cooled and/or condensed CO₂refrigerant from fluid conduit 3 and outputs the CO₂ refrigerant tofluid conduit 5. High pressure valve 4 may control the pressure of theCO₂ refrigerant in gas cooler/condenser 2 by controlling an amount ofCO₂ refrigerant permitted to pass through high pressure valve 4. In someembodiments, high pressure valve 4 is a high pressure thermal expansionvalve (e.g., if the pressure in fluid conduit 3 is greater than thepressure in fluid conduit 5). In such embodiments, high pressure valve 4may allow the CO₂ refrigerant to expand to a lower pressure state. Theexpansion process may be an isenthalpic and/or adiabatic expansionprocess, resulting in a flash expansion (e.g., a two-phase flash) of thehigh pressure CO₂ refrigerant to a lower pressure, lower temperaturestate. The expansion process may produce a liquid/vapor mixture (e.g.,having a thermodynamic vapor quality between 0 and 1). In someembodiments, the CO₂ refrigerant expands to a pressure of approximately38 bar (e.g., about 550 psig), which corresponds to a temperature ofapproximately 40° F. The CO₂ refrigerant then flows from fluid conduit 5into receiver 6.

Receiver 6 collects the CO₂ refrigerant from fluid conduit 5. In someembodiments, receiver 6 may be a flash tank or other fluid reservoir.Receiver 6 includes a CO₂ liquid portion 16 and a CO₂ vapor portion 15and may contain a partially saturated mixture of CO₂ liquid and CO₂vapor. In some embodiments, receiver 6 separates the CO₂ liquid from theCO₂ vapor. The CO₂ liquid may exit receiver 6 through fluid conduits 9.Fluid conduits 9 may be liquid headers leading to MT subsystem 10 and/orLT subsystem 20. The CO₂ vapor may exit receiver 6 through fluid conduit7. Fluid conduit 7 is shown leading the CO₂ vapor to a flash gas bypassvalve 8.

Still referring to FIGS. 1-2, MT subsystem 10 is shown to include one ormore expansion valves 11, one or more MT evaporators 12, and one or moreMT compressors 14. In various embodiments, any number of expansionvalves 11, MT evaporators 12, and MT compressors 14 may be present.Expansion valves 11 may be electronic expansion valves or other similarexpansion valves. Expansion valves 11 are shown receiving liquid CO₂refrigerant from fluid conduit 9 and outputting the CO₂ refrigerant toMT evaporators 12. Expansion valves 11 may cause the CO₂ refrigerant toundergo a rapid drop in pressure, thereby expanding the CO₂ refrigerantto a lower pressure, lower temperature two-phase state. In someembodiments, expansion valves 11 expand the CO₂ refrigerant to apressure of approximately 20 bar to 25 bar and a temperature ofapproximately 0° F. to 13° F. In other embodiments, expansion valves 11expand the CO₂ refrigerant to a pressure of approximately 30 bar. Theexpansion process may be an isenthalpic and/or adiabatic expansionprocess.

MT evaporators 12 are shown receiving the cooled and expanded CO₂refrigerant from expansion valves 11. In some embodiments, MTevaporators may be associated with display cases/devices (e.g., if CO₂refrigeration system 100 is implemented in a supermarket setting). MTevaporators 12 may be configured to facilitate the transfer of heat fromthe display cases/devices into the CO₂ refrigerant. The added heat maycause the CO₂ refrigerant to evaporate partially or completely.According to one embodiment, the CO₂ refrigerant is fully evaporated inMT evaporators 12. In some embodiments, the evaporation process may bean isobaric process. MT evaporators 12 are shown outputting the CO₂refrigerant via fluid conduits 13, leading to MT compressors 14.

MT compressors 14 compress the CO₂ refrigerant into a superheated gashaving a pressure within a range of approximately 45 bar toapproximately 100 bar. The output pressure from MT compressors 14 mayvary depending on ambient temperature and other operating conditions. Insome embodiments, MT compressors 14 operate in a transcritical mode. Inoperation, the CO₂ discharge gas exits MT compressors 14 and flowsthrough fluid conduit 1 into gas cooler/condenser 2.

Still referring to FIGS. 1-2, LT subsystem 20 is shown to include one ormore expansion valves 21, one or more LT evaporators 22, and one or moreLT compressors 24. In various embodiments, any number of expansionvalves 21, LT evaporators 22, and LT compressors 24 may be present. Insome embodiments, LT subsystem 20 may be omitted and the CO₂refrigeration system 100 may operate with only MT subsystem 10.

Expansion valves 21 may be electronic expansion valves or other similarexpansion valves. Expansion valves 21 are shown receiving liquid CO₂refrigerant from fluid conduit 9 and outputting the CO₂ refrigerant toLT evaporators 22. Expansion valves 21 may cause the CO₂ refrigerant toundergo a rapid drop in pressure, thereby expanding the CO₂ refrigerantto a lower pressure, lower temperature two-phase state. The expansionprocess may be an isenthalpic and/or adiabatic expansion process. Insome embodiments, expansion valves 21 may expand the CO₂ refrigerant toa lower pressure than expansion valves 11, thereby resulting in a lowertemperature CO₂ refrigerant. Accordingly, LT subsystem 20 may be used inconjunction with a freezer system or other lower temperature displaycases.

LT evaporators 22 are shown receiving the cooled and expanded CO₂refrigerant from expansion valves 21. In some embodiments, LTevaporators may be associated with display cases/devices (e.g., if CO₂refrigeration system 100 is implemented in a supermarket setting). LTevaporators 22 may be configured to facilitate the transfer of heat fromthe display cases/devices into the CO₂ refrigerant. The added heat maycause the CO₂ refrigerant to evaporate partially or completely. In someembodiments, the evaporation process may be an isobaric process. LTevaporators 22 are shown outputting the CO₂ refrigerant via fluidconduit 23, leading to LT compressors 24.

LT compressors 24 compress the CO₂ refrigerant. In some embodiments, LTcompressors 24 may compress the CO₂ refrigerant to a pressure ofapproximately 30 bar (e.g., about 450 psig) having a saturationtemperature of approximately 23° F. In some embodiments, LT compressors24 operate in a subcritical mode. LT compressors 24 are shown outputtingthe CO₂ refrigerant through fluid conduit 25. Fluid conduit 25 may befluidly connected with the suction (e.g., upstream) side of MTcompressors 14.

Still referring to FIGS. 1-2, CO₂ refrigeration system 100 is shown toinclude a gas bypass valve 8. Gas bypass valve 8 may receive the CO₂vapor from fluid conduit 7 and output the CO₂ refrigerant to MTsubsystem 10. In some embodiments, gas bypass valve 8 is arranged inseries with MT compressors 14. In other words, CO₂ vapor from receiver 6may pass through both gas bypass valve 8 and MT compressors 14. MTcompressors 14 may compress the CO₂ vapor passing through gas bypassvalve 8 from a low pressure state (e.g., approximately 30 bar or lower)to a high pressure state (e.g., 45-100 bar).

Gas bypass valve 8 may be operated to regulate or control the pressurewithin receiver 6 (e.g., by adjusting an amount of CO₂ refrigerantpermitted to pass through gas bypass valve 8). For example, gas bypassvalve 8 may be adjusted (e.g., variably opened or closed) to adjust themass flow rate, volume flow rate, or other flow rates of the CO₂refrigerant through gas bypass valve 8. Gas bypass valve 8 may be openedand closed (e.g., manually, automatically, by a controller, etc.) asneeded to regulate the pressure within receiver 6.

In some embodiments, gas bypass valve 8 includes a sensor for measuringa flow rate (e.g., mass flow, volume flow, etc.) of the CO₂ refrigerantthrough gas bypass valve 8. In other embodiments, gas bypass valve 8includes an indicator (e.g., a gauge, a dial, etc.) from which theposition of gas bypass valve 8 may be determined. This position may beused to determine the flow rate of CO₂ refrigerant through gas bypassvalve 8, as such quantities may be proportional or otherwise related.

In some embodiments, gas bypass valve 8 may be a thermal expansion valve(e.g., if the pressure on the downstream side of gas bypass valve 8 islower than the pressure in fluid conduit 7). According to oneembodiment, the pressure within receiver 6 is regulated by gas bypassvalve 8 to a pressure of approximately 38 bar, which corresponds toabout 37° F. Advantageously, this pressure/temperature state mayfacilitate the use of copper tubing/piping for the downstream CO₂ linesof the system. Additionally, this pressure/temperature state may allowsuch copper tubing to operate in a substantially frost-free manner.

In some embodiments, the CO₂ vapor that is bypassed through gas bypassvalve 8 is mixed with the CO₂ refrigerant gas exiting MT evaporators 12(e.g., via fluid conduit 13). The bypassed CO₂ vapor may also mix withthe discharge CO₂ refrigerant gas exiting LT compressors 24 (e.g., viafluid conduit 25). The combined CO₂ refrigerant gas may be provided tothe suction side of MT compressors 14.

Still referring to FIGS. 1-2, CO₂ refrigeration system 100 is shown toinclude a magnetic refrigeration system (MRS) 30. MRS 30 can beconfigured to perform a magnetocaloric refrigeration cycle (i.e., arefrigeration cycle that uses the magnetocaloric effect) to provideafter-cooling for the CO₂ refrigerant in fluid conduit 3. Relative totraditional, compressor-based air conditioning systems, MRS 30 mayconsume substantially less electrical power in providing comparablelevels of cooling.

MRS 30 is shown to include a heat exchanger 31, a magnetocaloricconditioning unit 32, a pump 33, and a heat sink 34. Pump 33 may operateto circulate a coolant (e.g., water, glycol, a mixture of water andpropylene glycol, etc.) through a coolant circuit 37 that fluidlycouples heat exchanger 31, magnetocaloric conditioning unit 32, pump 33,and heat sink 34. Pump 33 may provide a substantially constant flow rateof the coolant, oscillating flow rates of the coolant, or pulses ofcoolant flow. Pump 33 may provide coolant to magnetocaloric conditioningunit 32 as needed to maximize the efficiency of the magnetocaloriccooling process.

Coolant circuit 37 is shown to include a first fluid conduit 35 thatdelivers the coolant from heat sink 34 to heat exchanger 31 and a secondfluid conduit 36 that delivers the coolant from heat exchanger 31 toheat sink 34. Heat sink 34 may receive a supply of hot coolant via fluidconduit 36 and may transfer heat from the coolant to the ambientenvironment, thereby reducing the temperature of the coolant. Heat sink34 may output a supply of reduced-temperature (e.g., warm) coolant intofluid conduit 35. In various embodiments, heat sink 34 may be positionedoutdoors and exposed to outdoor ambient air or may be located indoorsand exposed to a relatively constant indoor temperature. In someembodiments, the temperature of the coolant in fluid conduit 35 may be asingle year-round fixed temperature related to the highest temperatureof heat sink 34 and may be controlled to be independent of fluctuationsin the temperature of heat sink 34. In other embodiments, thetemperature of the coolant in fluid conduit 35 may be controlled to orallowed to “float” to different temperatures correlating withtemperature of heat sink 34 at any given moment.

Heat exchanger 31 may be positioned along fluid conduit 3 and configuredto transfer heat from the CO₂ refrigerant in fluid conduit 3 to thecoolant in MRS 30. In some embodiments, heat exchanger 31 is positioneddownstream of gas cooler/condenser 2 and provides additional cooling(i.e., after-cooing) for the CO₂ refrigerant exiting gascooler/condenser 2. This lowers the temperature of the CO₂ refrigerantentering high pressure valve 4, which causes the colder CO₂ refrigerantto produce less flash gas than it would otherwise as it enters receiver6. The reduction in the amount of flash gas causes a reduction in theamount of energy required for recompressing flash gas at MT compressors14. Heat exchanger 31 may receive a supply of chilled coolant via fluidconduit 35, transfer heat from the CO₂ refrigerant into the coolant, andoutput the heated coolant via fluid conduit 36.

Magnetocaloric conditioning unit 32 may be fluidly coupled to both fluidconduits 35 and 36 and configured to transfer heat from the coolant influid conduit 35 to the coolant in fluid conduit 36. Magnetocaloricconditioning unit 32 may receive a supply of warm coolant from heat sink34 via fluid conduit 35 as well as a supply of cool coolant from heatexchanger 31 via fluid conduit 36. Magnetocaloric conditioning unit 32may transfer heat from the cool coolant in fluid conduit 35 to the warmcoolant in fluid conduit 36, thereby providing additional cooling forthe coolant entering heat exchanger 31.

Magnetocaloric conditioning unit 32 may perform a magnetocaloricrefrigeration cycle (i.e., a refrigeration cycle that uses themagnetocaloric effect) to cool the coolant provided to heat exchanger31. In some embodiments, magnetocaloric conditioning unit 32 useschanging magnetic fields to remove heat from the coolant in fluidconduit 35. The coolant in fluid conduit 35 thereby emerges frommagnetocaloric conditioning unit 32 and enters heat exchanger 31 at acold temperature. In some embodiments, magnetocaloric conditioning unitis made at least partially of a specialty alloy with a substantialmagnetocaloric effect (e.g., gadolinium or synthetic alloy), and one ormore magnets capable of generating a variable magnetic field around thespecialty alloy (e.g., by moving relative to the specialty alloy, byvarying in field strength).

In some embodiments, the specialty alloy in magnetocaloric conditioningunit 32 starts at room temperature. A magnetic field can be applied tothe specialty alloy, which causes the alloy to increase in temperaturedue to magnetic properties of the alloy. With the magnetic field heldconstant, heat can be transferred from the alloy into the coolant influid conduit 36. The magnetic field can then be removed, and themagnetic properties of the alloy cause the alloy to drop significantlyin temperature. The alloy then absorbs heat from the coolant in fluidconduit 35, causing the coolant to decrease in temperature. The coolantis thereby cooled by magnetocaloric conditioning unit 32. Due toproperties of the specialty alloy, the increase in temperature of thealloy caused by the magnetic field may be substantially less than thedecrease in temperature of the alloy caused by the removal of themagnetic field, resulting in a net decrease in temperature that can beapplied to the coolant.

Various arrangements of coolant tube(s), magnets, and specialty alloysin magnetocaloric conditioning unit 32 are possible in variousembodiments. In one example, the coolant flows through the center of acylinder made of the specialty alloy. Magnets can be positioned aroundthe specialty alloy. Varying power may be provided to electromagnets tovary the magnetic field. The coolant can then be pumped through thecylinder so that heat from the coolant is absorbed by the cylinder andthe coolant is cooled and provided to heat exchanger 31. In variousembodiments, magnetocaloric conditioning unit 32 includes a spinningdisk, actuating pole, or spinning pole. It is contemplated that any typeor configuration of magnetocaloric conditioning unit 32 can be used inMRS 30.

Referring particularly to FIG. 2, in some embodiments, MRS 30 includes abypass conduit connecting fluid conduits 35 and 36. Bypass conduit 39may provide an alternative path for the coolant to flow from fluidconduit 35 to fluid conduit 36 without passing through heat exchanger31. In some embodiments, a control valve 38 is located along bypassconduit 39 or at the intersection of bypass conduit 39 and fluid conduit36. Control valve 38 can be operated to control the flow of coolantthrough bypass conduit 39 and/or the flow of coolant through heatexchanger 31. In some embodiments, control valve 38 is operated to limitthe amount of heat gained by the coolant in heat exchanger 31. Forexample, control valve 38 can be operated to minimize the amount of heatgained by the coolant in heat exchanger 31 to prevent MRS 30 from beingoverwhelmed.

In some embodiments, control valve 38 is operated to control the flow ofcoolant into heat exchanger 31 based on mixed fluid temperature of thecoolant in fluid conduit 36 downstream of control valve 38. For example,MRS 30 may include a temperature sensor positioned along fluid conduit36 between control valve 38 and magnetocaloric conditioning unit 32 andconfigured to measure the temperature of the coolant at the location ofthe temperature sensor. Control valve 38 can be operated to maintain themeasured temperature of the mixed coolant (i.e., a mixture of thecoolant exiting heat exchanger 31 and the coolant bypassing heatexchanger 31 via bypass conduit 39) at a predetermined temperaturesetpoint. Control valve 38 can be opened more to allow more of the coldcoolant to bypass heat exchanger 31 via bypass conduit 39 in order todecrease the temperature of the mixed coolant, or closed more to allowless of the cold coolant to bypass heat exchanger 31 via bypass conduit39 in order to increase the temperature of the mixed coolant.

CO₂ Refrigeration System with Magnetic Refrigeration System After-Coolerand Desuperheater

Referring now to FIG. 3, another a CO₂ refrigeration system 110 isshown, according to an exemplary embodiment. CO₂ refrigeration system110 is shown to include many of the same components as CO₂ refrigerationsystem 100, as described with reference to FIGS. 1-2. These componentsof CO₂ refrigeration system 110 (i.e., any component having the samereference number as a component of CO₂ refrigeration system 100) mayhave the same or similar configuration as the corresponding componentsof CO₂ refrigeration system 100 and may perform the same or similarfunctions as the corresponding components of CO₂ refrigeration system100, as previously described with reference to FIGS. 1-2. Accordingly,the description of these components is not repeated here.

CO₂ refrigeration system 110 is shown to include a desuperheat heatexchanger 42. Desuperheat heat exchanger 42 may be positioned alongfluid conduit 25 (i.e., the CO₂ refrigerant discharge line for LTcompressors 24) and configured to absorb heat from the CO₂ refrigerantin fluid conduit 25, thereby decreasing the amount of superheat of theCO₂ refrigerant in fluid conduit 25. Coolant from MRS 30 may be providedto desuperheat heat exchanger 42 to provide cooling for the CO₂refrigerant in desuperheat heat exchanger 42. Desuperheat heat exchanger42 may transfer heat from the CO₂ refrigerant in fluid conduit 25 intothe coolant from MRS 30, thereby cooling the CO₂ refrigerant and heatingthe coolant from MRS 30.

In some embodiments, a first fluid conduit 41 provides coolant from MRS30 to desuperheat heat exchanger 42 and a second fluid conduit 43returns the heated coolant from desuperheat heat exchanger 42 to MRS 30.As shown in FIG. 3, fluid conduit 41 may be connected to fluid conduit36 at a first connection point between heat exchanger 31 andmagnetocaloric conditioning unit 32 and configured to deliver thecoolant from fluid conduit 36 to desuperheat heat exchanger 42.Similarly, fluid conduit 43 may be connected to fluid conduit 36 at asecond connection point between heat exchanger 31 and magnetocaloricconditioning unit 32 (downstream of the first connection point) andconfigured to return the coolant from desuperheat heat exchanger 42 tofluid conduit 36.

CO₂ refrigeration system 110 may include one or more fluid controlvalves operable to control the flow of coolant to desuperheat heatexchanger 42. For example, CO₂ refrigeration system 110 is shown toinclude a control valve 44. Control valve 44 may be positioned alongeither of fluid conduits 41 or 43, at the intersection of fluid conduits41 and 36, or at the intersection of fluid conduits 43 and 36. Controlvalve 44 can be operated to control the flow of coolant through fluidconduit 41, desuperheat heat exchanger 42, and fluid conduit 43. Controlvalve 38 may also be included in CO₂ refrigeration system 110(performing the same function as previously described) or can be omittedfrom CO₂ refrigeration system 110 in various embodiments.

In some embodiments, control valves 44 and/or 38 are operated toincrease the amount of heat transferred from the CO₂ refrigerant to thecoolant in MRS 30. This allows MRS 30 to operate at its maximum capacitymore often and thus maximize the energy reduction that MRS 30 providesto CO₂ refrigeration system 110. In some embodiments, control valves 44and/or 38 are operated based on the temperature of the coolant providedby MRS 30 at various locations within MRS 30 (e.g., within any of thefluid conduits that contain coolant) and/or the temperature of the CO₂refrigerant at various locations within CO₂ refrigeration system 110.For example, the temperatures of the coolant and/or the CO₂ refrigerantcan be used to control the amount of coolant provided to heat exchanger31 and/or desuperheat heat exchanger 42 depending on where heatcollection is needed. Although only one desuperheat heat exchanger 42 isshown in FIG. 3, it is contemplated that any number of heat exchangerscan be added to CO₂ refrigeration system 110 to collect heat from thatCO₂ refrigerant at any location within CO₂ refrigeration system 110.

In some embodiments, control valves 44 and/or 38 are operated to controlthe amount of heat transferred from the CO₂ refrigerant to the coolantin MRS 30 based on the temperature of the mixed coolant returning to MRS30 from heat exchanger 42. For example, a temperature sensor can bepositioned along fluid conduit 36 between control valve 44 andmagnetocaloric conditioning unit 32 and configured to measure thetemperature of the mixed coolant at the location of the temperaturesensor. Control valve 44 can be operated to control the flow of coolantto heat exchanger 42 based on the temperature of the mixed coolant.

In other embodiments, control valves 44 and/or 38 are operated tocontrol the amount of heat transferred from the CO₂ refrigerant to thecoolant in MRS 30 based on the temperature and/or pressure of the CO₂refrigerant as it exits from heat exchanger 42. Temperature and/orpressure sensors can be positioned to measure the temperature/pressureof the CO₂ refrigerant at the exit of desuperheat heat exchanger 42.Controlling the flow of coolant to desuperheat heat exchanger 42 basedon the temperature and/or pressure of the CO₂ refrigerant at the exit ofdesuperheat exchanger 42 allows for a specific amount of superheat to bemaintained in the CO₂ refrigerant exiting desuperheat heat exchanger 42.

In some embodiments, the coolant from MRS 30 is supplied to desuperheatheat exchanger 42 (and/or other heat exchangers added to CO₂refrigeration system 110) after first gathering heat from the CO₂refrigerant in heat exchanger 31, as shown in FIG. 3. In otherembodiments, the coolant from MRS 30 can be supplied to desuperheat heatexchanger 42 (and/or other heat exchangers added to CO₂ refrigerationsystem 110) in parallel with heat exchanger 31. For example, fluidconduit 41 may connect to fluid conduit 35 rather than fluid conduit 36such that the cold coolant from fluid conduit 35 is provided todesuperheat heat exchanger 42. In other embodiments, the coolant fromMRS 30 can be supplied to desuperheat heat exchanger 42 (and/or otherheat exchangers added to CO₂ refrigeration system 110) before flowingthrough heat exchanger 31. For example, both fluid conduits 41 and 43may connect to fluid conduit 35 rather than fluid conduit 36 such thatthe cold coolant from fluid conduit 35 is provided to desuperheat heatexchanger 42 and the coolant from desuperheat heat exchanger 42 isreturned to fluid conduit 35. In other embodiments, the coolant from MRS30 can be supplied to desuperheat heat exchanger 42 (and/or other heatexchangers added to CO₂ refrigeration system 110) instead of flowing toheat exchanger 31. For example, heat exchanger 31 can be omitted fromCO₂ refrigeration system 110 in some embodiments and is not a requiredcomponent.

CO₂ Refrigeration System with Magnetic Refrigeration System as a MTSuction Condenser Applied with a Liquid Ejector

Referring now to FIG. 4, another a CO₂ refrigeration system 120 isshown, according to an exemplary embodiment. CO₂ refrigeration system120 is shown to include many of the same components as CO₂ refrigerationsystems 100 and 110, as described with reference to FIGS. 1-3. Thesecomponents of CO₂ refrigeration system 120 (i.e., any component havingthe same reference number as a component of CO₂ refrigeration systems100 or 110) may have the same or similar configuration as thecorresponding components of CO₂ refrigeration systems 100 or 110 and mayperform the same or similar functions as the corresponding components ofCO₂ refrigeration systems 100 or 110, as previously described withreference to FIGS. 1-3. Accordingly, the description of these componentsis not repeated here.

CO₂ refrigeration system 120 is shown to include a heat exchanger 53.Heat exchanger 53 may be configured to provide cooling for the CO₂refrigerant in fluid conduit 13 (i.e., the suction line for MTcompressors 14). Heat exchanger 53 may absorb heat from the CO₂refrigerant in fluid conduit 13. Like heat exchanger 31 of CO₂refrigeration systems 100 or 110, heat exchanger 53 may receive coolantfrom MRS 30 via fluid conduit 35 and may return coolant to MRS 30 viafluid conduit 36. Coolant from MRS 30 may be provided to heat exchanger53 via fluid conduit 35 to provide cooling for the CO₂ refrigerant inheat exchanger 53. Heat exchanger 53 may transfer heat from the CO₂refrigerant in fluid conduit 13 into the coolant from MRS 30, therebycooling the CO₂ refrigerant and heating the coolant from MRS 30. Theheated coolant may then return to MRS 30 via fluid conduit 36.

In some embodiments, the temperature of the coolant supplied to heatexchanger 53 is controlled such that it will cause the CO₂ refrigerantvapor from fluid conduit 13 to condense (fully or partially) in heatexchanger 53. The condensed CO₂ liquid or liquid/vapor mixture may exitheat exchanger 53 via fluid conduit 54 and may be collected in aliquid/vapor separator 52. Liquid CO₂ refrigerant within liquid/vaporseparator 52 can be delivered to receiver 6 via fluid conduits 55 and 5.In some embodiments, the pressure within receiver 6 is higher than thepressure within liquid/vapor separator 52. Accordingly, a motive forcemay be required to move the liquid CO₂ refrigerant from liquid/vaporseparator 52 to receiver 6. In various embodiments, the motive force maybe supplied by gravity (e.g., by locating liquid/vapor separator 52 at ahigher elevation than receiver 6) or by a mechanical device such as apump or an ejector 51. For example, ejector 51 may be located at theintersection of fluid conduits 55 and 5 (in place of high pressure valve4 or installed in parallel to high pressure valve 4 shown in FIGS. 1-3)and configured to force the liquid CO₂ refrigerant from fluid conduit 55into receiver 6 via fluid conduit 5.

In some embodiments, control valve 38 is operated to increase the amountof heat transferred from the CO₂ refrigerant to the coolant in MRS 30.This allows MRS 30 to operate at its maximum capacity more often andthus maximize the energy reduction that MRS 30 provides to CO₂refrigeration system 120. In some embodiments, control valve 38 isoperated based on the temperature of the coolant provided by MRS 30 atvarious locations within MRS 30 (e.g., within any of the fluid conduitsthat contain coolant) and/or the temperature of the CO₂ refrigerant atvarious locations within CO₂ refrigeration system 120. For example, thetemperatures of the coolant and/or the CO₂ refrigerant can be used tocontrol the amount of coolant provided to heat exchanger 53.

In some embodiments, control valve 38 is operated to control the amountof heat transferred from the CO₂ refrigerant to the coolant in MRS 30based on the temperature of the mixed coolant returning to MRS 30 fromheat exchanger 53. For example, a temperature sensor can be positionedalong fluid conduit 36 between control valve 38 and magnetocaloricconditioning unit 32 and configured to measure the temperature of themixed coolant at the location of the temperature sensor (e.g., after thecoolant returning from heat exchanger 53 mixes with the coolantbypassing heat exchanger 53 via bypass conduit 39). Control valve 38 canbe operated to control the flow of coolant to heat exchanger 53 based onthe temperature of the mixed coolant. In some embodiments, a temperaturesensor can be positioned along fluid conduit 36 upstream of controlvalve 38 and configured to measure the temperature of the coolantexiting heat exchanger 53 (e.g., before the coolant returning from heatexchanger 53 mixes with the coolant bypassing heat exchanger 53 viabypass conduit 39). Control valve 38 can be operated to control the flowof coolant to heat exchanger 53 based on the temperature of the coolantexiting heat exchanger 53.

In other embodiments, control valve 38 is operated to control the amountof heat transferred from the CO₂ refrigerant to the coolant in MRS 30based on the temperature and/or pressure of the CO₂ refrigerant as itexits from heat exchanger 53. Temperature and/or pressure sensors can bepositioned to measure the temperature/pressure of the CO₂ refrigerant atthe exit of heat exchanger 53. Controlling the flow of coolant to heatexchanger 53 based on the temperature and/or pressure of the CO₂refrigerant at the exit of exchanger 53 allows for a specific amount ofsuperheat to be maintained in the CO₂ refrigerant exiting heat exchanger53. The amount of heat transferred from the CO₂ refrigerant to thecoolant in MRS 30 can also (or alternatively) be controlled by adjustingthe temperature of the coolant supplied to heat exchanger 53 (e.g., bycontrolling the operation of magnetocaloric conditioning unit 32)without requiring the use of control valve 38.

CO₂ Refrigeration System with Magnetic Refrigeration System as a LTDischarge Gas Condenser and Flash Gas Condenser Applied with ParallelCompression

Referring now to FIG. 5, another a CO₂ refrigeration system 130 isshown, according to an exemplary embodiment. CO₂ refrigeration system130 is shown to include many of the same components as CO₂ refrigerationsystems 100, 110, and 120, as described with reference to FIGS. 1-4.These components of CO₂ refrigeration system 130 (i.e., any componenthaving the same reference number as a component of CO₂ refrigerationsystems 100, 110, or 120) may have the same or similar configuration asthe corresponding components of CO₂ refrigeration systems 100, 110, or120 and may perform the same or similar functions as the correspondingcomponents of CO₂ refrigeration systems 100, 110, or 120 as previouslydescribed with reference to FIGS. 1-4. Accordingly, the description ofthese components is not repeated here.

CO₂ refrigeration system 130 is shown to include a heat exchanger 61.Heat exchanger 61 may be configured to provide cooling for the CO₂refrigerant in fluid conduit 25 (i.e., the discharge line for LTcompressors 24). Heat exchanger 61 may absorb heat from the CO₂refrigerant vapor in fluid conduit 25, thereby causing the CO₂refrigerant in fluid conduit 25 to condense into a liquid. Like heatexchanger 31 of CO₂ refrigeration systems 100 or 110, heat exchanger 61may receive coolant from MRS 30 via fluid conduit 35 and may returncoolant to MRS 30 via fluid conduit 36. Coolant from MRS 30 may beprovided to heat exchanger 61 via fluid conduit 35 to provide coolingfor the CO₂ refrigerant in heat exchanger 61. Heat exchanger 61 maytransfer heat from the CO₂ refrigerant in fluid conduit 25 into thecoolant from MRS 30, thereby cooling the CO₂ refrigerant and heating thecoolant from MRS 30. The heated coolant may then return to MRS 30 viafluid conduit 36.

In some embodiments, the temperature of the coolant supplied to heatexchanger 61 is controlled such that it will cause the CO₂ refrigerantvapor from fluid conduit 25 to fully condense in heat exchanger 61. Thecondensed CO₂ refrigerant liquid may exit heat exchanger 61 via fluidconduit 62 and may be collected in receiver 6. Heat exchanger 61 may belocated in line between LT compressor discharge line 25 and receiver 6(as shown in FIG. 5) or may be independently connected to receiver 6.MRS 30 may be sized and/or controlled to manage the CO₂ vapor inreceiver 6 by condensing all of the CO₂ refrigerant vapor present inreceiver 6. In some embodiments, MRS 30 manages the CO₂ refrigerantvapor in receiver 6 by working in parallel with a parallel compressor63. Parallel compressor 63 may be connected to the vapor portion 15 ofreceiver 6 (e.g., via fluid conduits 7 and 66) and configured tocompress the CO₂ refrigerant vapor. In various embodiments, parallelcompressor 63 may work in parallel with MT compressors 14 or may beimplemented as a replacement for MT compressors 14 (i.e., MT compressors14 and/or other portions of MT subsystem 10 can be omitted).

In some embodiments, parallel compressor 63 may be operated (e.g., by acontroller) to achieve a desired pressure within receiver 6. Forexample, the controller may receive pressure measurements from apressure sensor monitoring the pressure within receiver 6 and mayactivate or deactivate parallel compressor 63 based on the pressuremeasurements. When active, parallel compressor 63 compresses the CO₂vapor received via connecting line 66 and discharges the compressedvapor into connecting line 67. Connecting line 67 may be fluidlyconnected with fluid conduit 1. Accordingly, parallel compressor 63 mayoperate in parallel with MT compressors 14 by discharging the compressedCO₂ vapor into a shared fluid conduit (e.g., fluid conduit 1).

Parallel compressor 63 may be arranged in parallel with both gas bypassvalve 8 and with MT compressors 14. In other words, CO₂ vapor exitingreceiver 6 may pass through either parallel compressor 63 or the seriescombination of gas bypass valve 8 and MT compressors 14. Parallelcompressor 63 may receive the CO₂ vapor at a relatively higher pressure(e.g., from fluid conduits 7 and 66) than the CO₂ vapor received by MTcompressors 14 (e.g., from fluid conduit 13). This differential inpressure may correspond to the pressure differential across gas bypassvalve 8. In some embodiments, parallel compressor 63 may require lessenergy to compress an equivalent amount of CO₂ vapor to the highpressure state (e.g., in fluid conduit 1) as a result of the higherpressure of CO₂ vapor entering parallel compressor 63. Therefore, theparallel route including parallel compressor 63 may be a more efficientalternative to the route including gas bypass valve 8 and MT compressors14.

In some embodiments, gas bypass valve 8 is omitted and the pressurewithin receiver 6 is regulated using parallel compressor 63. In otherembodiments, parallel compressor 63 is omitted and the pressure withinreceiver 6 is regulated using gas bypass valve 8. In other embodiments,both gas bypass valve 8 and parallel compressor 6 are used to regulatethe pressure within receiver 6. All such variations are within the scopeof the present disclosure.

In some embodiments, CO₂ refrigeration system 130 includes a heatexchanger 65. Heat exchanger 65 may be positioned along fluid conduit 3and can be configured to condense (fully or partially) the CO₂refrigerant in fluid conduit 3. Heat exchanger 65 may also receive CO₂refrigerant vapor from receiver 6 via fluid conduit 7. A control valve64 can be operated to regulate the flow of CO₂ refrigerant vapor fromreceiver 6 into heat exchanger 65. Heat exchanger 65 may transfer heatfrom the CO₂ refrigerant in fluid conduit 3 into the CO₂ refrigerantvapor in fluid conduit 66, thereby providing additional cooling for theCO₂ refrigerant entering receiver 6. The heated CO₂ refrigerant vapor influid conduit 66 may be routed to parallel compressor 63 and compressedas previously described. Control valve 64 can be operated to control theamount of CO₂ refrigerant vapor routed through heat exchanger 65 and/orthe amount of CO₂ refrigerant vapor that flows from fluid conduit 7directly into fluid conduit 66 (bypassing heat exchanger 65).

CO₂ Refrigeration System with Magnetic Refrigeration System to Sub-CoolSupply Liquid

Referring now to FIG. 6, another a CO₂ refrigeration system 140 isshown, according to an exemplary embodiment. CO₂ refrigeration system140 is shown to include many of the same components as CO₂ refrigerationsystems 100, 110, 120, and 130, as described with reference to FIGS.1-4. These components of CO₂ refrigeration system 140 (i.e., anycomponent having the same reference number as a component of CO₂refrigeration systems 100, 110, 120, and 130) may have the same orsimilar configuration as the corresponding components of CO₂refrigeration systems 100, 110, 120, and 130 and may perform the same orsimilar functions as the corresponding components of CO₂ refrigerationsystems 100, 110, 120, and 130 as previously described with reference toFIGS. 1-5. Accordingly, the description of these components is notrepeated here.

CO₂ refrigeration system 140 is substantially the same as CO₂refrigeration system 100, with the exception that heat exchanger 31 ofMRS 30 is located along fluid conduit 9 (i.e., the CO₂ liquid supplyline exiting receiver 6) rather than fluid conduit 3. Fluid conduit 9may supply liquid CO₂ refrigerant to both MT evaporators 12 and LTevaporators 22. Using MRS 30 to extract heat from the liquid CO₂refrigerant in fluid conduit 9 may subcool the saturated liquid CO₂refrigerant from receiver 6 to a colder temperature than the CO₂refrigerant gas (i.e., flash gas) in receiver 6 without reducing thepressure within fluid conduit 9. This will enhance the liquid quality ofthe CO₂ refrigerant (i.e., reduce the quality of the saturatedliquid/gas mixture toward zero) as it enters expansion valves 11 and 21,and thus increase the amount of heat that the CO₂ refrigerant can absorbthrough evaporation in evaporators 12 and 22. As more heat energy can beabsorbed per unit mass of the CO₂ refrigerant, compressors 14 and 24will not be required to process as much mass flow to match the samerefrigeration load. Advantageously, this may decrease the requiredamount of energy consumption.

CO₂ Refrigeration System with Magnetic Refrigeration System to ConvertFlash Gas to Liquid Before Entering Flash Tank (Receiver)

Referring now to FIG. 7, another a CO₂ refrigeration system 150 isshown, according to an exemplary embodiment. CO₂ refrigeration system150 is shown to include many of the same components as CO₂ refrigerationsystems 100, 110, 120, 130, and 140, as described with reference toFIGS. 1-6. These components of CO₂ refrigeration system 150 (i.e., anycomponent having the same reference number as a component of CO₂refrigeration systems 100, 110, 120, 130, and 140) may have the same orsimilar configuration as the corresponding components of CO₂refrigeration systems 100, 110, 120, 130, and 140 and may perform thesame or similar functions as the corresponding components of CO₂refrigeration systems 100, 110, 120, 130, and 140 as previouslydescribed with reference to FIGS. 1-6. Accordingly, the description ofthese components is not repeated here.

CO₂ refrigeration system 150 is substantially the same as CO₂refrigeration system 100, with the exception that heat exchanger 31 ofMRS 30 is located along fluid conduit 5 (i.e., the fluid conduitconnecting high pressure valve 4 to receiver 6) rather than fluidconduit 3. Placing heat exchanger 31 of MRS 30 along fluid conduit 5will provide cooling for the CO₂ refrigerant entering receiver andreduce the amount of flash gas seen in receiver 6. Advantageously, thismay reduce the power required by MT compressors 14 to process theshort-circuited CO₂ refrigerant gas.

Configuration of Exemplary Embodiments

The construction and arrangement of the CO₂ refrigeration systems asshown in the various exemplary embodiments are illustrative only.Although only a few embodiments have been described in detail in thisdisclosure, those skilled in the art who review this disclosure willreadily appreciate that many modifications are possible (e.g.,variations in sizes, dimensions, structures, shapes and proportions ofthe various elements, values of parameters, mounting arrangements, useof materials, colors, orientations, etc.) without materially departingfrom the novel teachings and advantages of the subject matter describedherein. For example, elements shown as integrally formed may beconstructed of multiple parts or elements, the position of elements maybe reversed or otherwise varied, and the nature or number of discreteelements or positions may be altered or varied. The order or sequence ofany process or method steps may be varied or re-sequenced according toalternative embodiments. Other substitutions, modifications, changes andomissions may also be made in the design, operating conditions andarrangement of the various exemplary embodiments without departing fromthe scope of the present invention.

As utilized herein, the terms “approximately,” “about,” “substantially”,and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed and claimed without restricting the scope of these features tothe precise numerical ranges provided. Accordingly, these terms shouldbe interpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and claimedare considered to be within the scope of the invention as recited in theappended claims.

It should be noted that the term “exemplary” as used herein to describevarious embodiments is intended to indicate that such embodiments arepossible examples, representations, and/or illustrations of possibleembodiments (and such term is not intended to connote that suchembodiments are necessarily extraordinary or superlative examples).

The terms “coupled,” “connected,” and the like as used herein mean thejoining of two members directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent) or moveable (e.g., removableor releasable). Such joining may be achieved with the two members or thetwo members and any additional intermediate members being integrallyformed as a single unitary body with one another or with the two membersor the two members and any additional intermediate members beingattached to one another.

References herein to the positions of elements (e.g., “top,” “bottom,”“above,” “below,” etc.) are merely used to describe the orientation ofvarious elements in the FIGURES. It should be noted that the orientationof various elements may differ according to other exemplary embodiments,and that such variations are intended to be encompassed by the presentdisclosure.

The present disclosure contemplates methods, systems and programproducts on memory or other machine-readable media for accomplishingvarious operations. The embodiments of the present disclosure may beimplemented using existing computer processors, or by a special purposecomputer processor for an appropriate system, incorporated for this oranother purpose, or by a hardwired system. Embodiments within the scopeof the present disclosure include program products or memory includingmachine-readable media for carrying or having machine-executableinstructions or data structures stored thereon. Such machine-readablemedia can be any available media that can be accessed by a generalpurpose or special purpose computer or other machine with a processor.By way of example, such machine-readable media can comprise RAM, ROM,EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic diskstorage or other magnetic storage devices, or any other medium which canbe used to carry or store desired program code in the form ofmachine-executable instructions or data structures and which can beaccessed by a general purpose or special purpose computer or othermachine with a processor. Combinations of the above are also includedwithin the scope of machine-readable media. Machine-executableinstructions include, for example, instructions and data which cause ageneral purpose computer, special purpose computer, or special purposeprocessing machines to perform a certain function or group of functions.

Although the figures may show a specific order of method steps, theorder of the steps may differ from what is depicted. Also two or moresteps may be performed concurrently or with partial concurrence. Suchvariation will depend on the software and hardware systems chosen and ondesigner choice. All such variations are within the scope of thedisclosure. Likewise, software implementations could be accomplishedwith standard programming techniques with rule based logic and otherlogic to accomplish the various connection steps, processing steps,comparison steps and decision steps.

The background section is intended to provide a background or context tothe invention recited in the claims. The description in the backgroundsection may include concepts that could be pursued, but are notnecessarily ones that have been previously conceived or pursued.Therefore, unless otherwise indicated herein, what is described in thebackground section is not prior art to the description and claims ofthis disclosure and is not admitted to be prior art by inclusion in thebackground section.

Those skilled in the art will appreciate that the summary isillustrative only and is not intended to be in any way limiting. Otheraspects, inventive features, and advantages of the devices and/orprocesses described herein, as defined solely by the claims, will becomeapparent in the detailed description set forth herein and taken inconjunction with the accompanying drawings.

What is claimed is:
 1. A refrigeration system comprising: arefrigeration circuit comprising: a gas cooler/condenser configured toremove heat from a refrigerant circulating within the refrigerationcircuit and comprising an outlet through which the refrigerant exits thegas cooler/condenser; a receiver comprising an inlet fluidly coupled tothe outlet of the gas cooler/condenser and configured to collect therefrigerant from the gas cooler/condenser, the receiver furthercomprising an outlet through which the refrigerant exits the receiver;and an evaporator comprising an inlet fluidly coupled to the outlet ofthe receiver and configured to receive the refrigerant from thereceiver, the evaporator configured to transfer heat into therefrigerant circulating within the refrigeration circuit; and a coolantcircuit fluidly separate from the refrigeration circuit and comprising:a heat exchanger configured to transfer heat from the refrigerantcirculating within the refrigeration circuit into a coolant circulatingwithin the coolant circuit, the heat exchanger comprising a coolantinlet through which the coolant enters the heat exchanger and a coolantoutlet through which the coolant exits the heat exchanger; a heat sinkconfigured to remove heat from the coolant circulating within thecoolant circuit, the heat sink comprising an inlet fluidly coupled tothe coolant outlet of the heat exchanger and through which the coolantenters the heat sink, and comprising an outlet fluidly coupled to thecoolant inlet of the heat exchanger and through which the coolant exitsthe heat sink; and a magnetocaloric conditioning unit configured totransfer heat from the coolant within a first fluid conduit of thecoolant circuit into the coolant within a second fluid conduit of thecoolant circuit, the first fluid conduit fluidly coupling the coolantoutlet of the heat exchanger to the inlet of the heat sink, and thesecond fluid conduit fluidly coupling the outlet of the heat sink to thecoolant inlet of the heat exchanger.
 2. The refrigeration system ofclaim 1, wherein the magnetocaloric conditioning unit is configured toperform a magnetocaloric refrigeration cycle using changing magneticfields to transfer the heat from the coolant within the first fluidconduit into the coolant within the second fluid conduit.
 3. Therefrigeration system of claim 1, wherein the heat exchanger ispositioned along a fluid conduit of the refrigeration circuit connectingthe outlet of the gas cooler/condenser to the inlet of the receiver. 4.The refrigeration system of claim 3, the refrigeration circuit furthercomprising a high pressure valve positioned along the fluid conduitconnecting the outlet of the gas cooler/condenser to the inlet of thereceiver; wherein the heat exchanger is positioned between the gascooler/condenser and the high pressure valve to provide additionalcooling for the refrigerant exiting the gas cooler/condenser before therefrigerant reaches the high pressure valve.
 5. The refrigeration systemof claim 3, the refrigeration circuit further comprising a high pressurevalve positioned along the fluid conduit connecting the outlet of thegas cooler/condenser to the inlet of the receiver; wherein the heatexchanger is positioned between the high pressure valve and the receiverto provide cooling for the refrigerant traveling from the high pressurevalve to the receiver.
 6. The refrigeration system of claim 1, whereinthe heat exchanger is positioned along a fluid conduit of therefrigeration circuit connecting the outlet of the receiver to the inletof the evaporator to subcool the refrigerant exiting the receiver beforethe refrigerant reaches the evaporator.
 7. The refrigeration system ofclaim 1, wherein the coolant circuit comprises: a bypass conduit fluidlycoupling the second fluid conduit of the coolant circuit to the firstfluid conduit of the coolant circuit in parallel with the heatexchanger, thereby providing an alternative flow path for the coolant totravel from the second fluid conduit to the first fluid conduit withoutpassing through the heat exchanger; a control valve positioned along thebypass conduit and operable to control a flow of the coolant through atleast one of the bypass conduit and the heat exchanger.
 8. Therefrigeration system of claim 7, further comprising: a temperaturesensor positioned along the first fluid conduit between themagnetocaloric conditioning unit and a location at which the bypassconduit and the first fluid conduit intersect; and a controllerconfigured to operate the control valve to maintain a temperature of thecoolant measured by the temperature sensor at or below a temperaturesetpoint by varying an amount of the coolant permitted to bypass theheat exchanger via the bypass conduit.
 9. The refrigeration system ofclaim 1, the refrigeration circuit further comprising one or morecompressors configured to compress the refrigerant and discharge thecompressed refrigerant into a compressor discharge line; wherein theheat exchanger is positioned along the compressor discharge line andconfigured to remove heat from the compressed refrigerant in thecompressor discharge line.
 10. The refrigeration system of claim 9,further comprising: a control valve operable to control a flow of thecoolant through the heat exchanger; and a controller configured tooperate the control valve to maintain a superheat of the refrigerantexiting the heat exchanger at a predetermined superheat setpoint byvarying an amount of heat removed from the compressed refrigerant in theheat exchanger.
 11. The refrigeration system of claim 9, furthercomprising: a control valve operable to control a flow of the coolantthrough the heat exchanger; and a controller configured to operate thecontrol valve to cause the compressed refrigerant in the heat exchangerto fully condense to a liquid refrigerant by controlling an amount ofheat removed from the compressed refrigerant in the heat exchanger. 12.The refrigeration system of claim 11, wherein the heat exchangercomprises a refrigerant outlet fluidly coupled to the receiver andconfigured to deliver the liquid refrigerant from the heat exchanger tothe receiver.
 13. The refrigeration system of claim 1, wherein thecoolant circuit comprises a plurality of heat exchangers configured totransfer heat from the refrigerant circulating within the refrigerationcircuit into the coolant circulating within the coolant circuit, theplurality of heat exchangers comprising: a first heat exchangerpositioned along a fluid conduit of the refrigeration circuit connectingthe outlet of the gas cooler/condenser to the inlet of the receiver toprovide additional cooling for the refrigerant traveling from the gascooler/condenser to the receiver; and a second heat exchanger positionedalong a compressor discharge line of the refrigeration circuit andconfigured to remove heat from the refrigerant in the compressordischarge line.
 14. The refrigeration system of claim 1, therefrigeration circuit further comprising one or more compressorsconfigured to receive the refrigerant from a compressor suction line,compress the refrigerant, and discharge the compressed refrigerant intoa compressor discharge line; wherein the heat exchanger is positionedalong the compressor suction line and configured to remove heat from thecompressed refrigerant in the compressor suction line.
 15. Therefrigeration system of claim 14, wherein the heat removed from therefrigerant in the heat exchanger causes the refrigerant to at leastpartially condense into a liquid or a mixture of liquid and gas; therefrigeration circuit further comprising a liquid/vapor separatorfluidly coupled to a refrigerant outlet of the heat exchanger andconfigured to separate a liquid portion of the refrigerant exiting theheat exchanger from a gas portion of the refrigerant exiting the heatexchanger.
 16. The refrigeration system of claim 15, wherein theliquid/vapor separator comprises: a liquid refrigerant outlet fluidlycoupled to the inlet of the receiver and configured to deliver theliquid portion of the refrigerant to the receiver; and a gas refrigerantoutlet fluidly coupled to the compressor suction line and configured todeliver the gas portion of the refrigerant to the compressor suctionline.
 17. A magnetic refrigeration system comprising: a heat exchangerconfigured to transfer heat from a refrigerant circulating within arefrigeration circuit into a coolant circulating within a coolantcircuit, the heat exchanger comprising a coolant inlet through which thecoolant enters the heat exchanger and a coolant outlet through which thecoolant exits the heat exchanger; a heat sink configured to remove heatfrom the coolant circulating within the coolant circuit, the heat sinkcomprising an inlet fluidly coupled to the coolant outlet of the heatexchanger and through which the coolant enters the heat sink, andcomprising an outlet fluidly coupled to the coolant inlet of the heatexchanger and through which the coolant exits the heat sink; and amagnetocaloric conditioning unit configured to transfer heat from thecoolant within a first fluid conduit of the coolant circuit into thecoolant within a second fluid conduit of the coolant circuit, the firstfluid conduit fluidly coupling the coolant outlet of the heat exchangerto the inlet of the heat sink, and the second fluid conduit fluidlycoupling the outlet of the heat sink to the coolant inlet of the heatexchanger.
 18. The magnetic refrigeration system of claim 17, whereinthe magnetocaloric conditioning unit is configured to perform amagnetocaloric refrigeration cycle using changing magnetic fields totransfer the heat from the coolant within the first fluid conduit intothe coolant within the second fluid conduit.
 19. The magneticrefrigeration system of claim 17, further comprising: a control valveoperable to control a flow of the coolant through the heat exchanger;and a controller configured to operate the control valve to maintain asuperheat of the refrigerant exiting the heat exchanger at apredetermined superheat setpoint by varying an amount of heat removedfrom the refrigerant in the heat exchanger.
 20. The magneticrefrigeration system of claim 17, further comprising: a control valveoperable to control a flow of the coolant through the heat exchanger;and a controller configured to operate the control valve to cause therefrigerant in the heat exchanger to fully condense to a liquidrefrigerant by controlling an amount of heat removed from therefrigerant in the heat exchanger.